Well, another Birthday forgotten by your tipsy old hag of a Mother. She's disgusting, truly, but you're used to it now. Every year, another excuse. Walking into your bedroom, you're not surprised to see that she is stumbling in with a glass of wine. Oh, she HAS remembered your Birthday, but it seems a little late since you're already in bed.
She tells you that she'll do whatever you want. Twisted, angry with her, you scream, "Suck my dick!" Taken aback, she stumbles over and says she will... if that's really what you want.
You only meant it figuratively, but let her parade over to you. She's unsure, questions whether or not it would really be in any one's best interest if she actually did such a thing. Her indecisiveness annoys you, and after she begins to suck you off, you shove her face onto your cock.
She's grumbling about how you're being rough. Well, that's what she gets for forgetting your Birthday.